ABSTRACT The Ohio State University proposes to purchase a correlative optical tweezers-confocal microscopy instrument to address the critical need for combined single molecule force and fluorescence analysis. Single molecule force and fluorescence spectroscopies have revolutionized the ability of researchers in cellular and molecular biology, biochemistry, biophysics and biomedical engineering to answer key biological and health-related questions. Currently, these tools are largely restricted to laboratories with specific expertise in this area that have lab-built single molecule instruments. The LUMICKS C-Trap is the only commercially available instrument that combines optical tweezers-force spectroscopy with confocal fluorescence microscopy in an integrated instrument. The C- Trap is designed as a turn-key system that allows laboratories without expertise in single molecule force or fluorescence spectroscopy to perform state-of-art single molecule measurements and fluorescence analysis. Key features of the C-Trap include dual optical traps to manipulate biomolecules; 3-color confocal fluorescence to visualize biological processes; sub pN force resolution/detection; temperature control to measure biomolecular interactions at physiological temperature; micro and nano-stage control for absolute sample positioning; laminar flow microfluidics that allow high sample throughput; and software that integrates, controls and automates the instrument components and data collection. An important aspect of the C-Trap is that its intuitive interface and automation package will allow non-expert users to learn how to run experiments and collect data after minimal training. This proposal is being submitted on behalf of four major users (all with NIH R01 funding) and eight minor users with either NIH or other funding. These users come from eight different departments (Biological Chemistry and Pharmacology, Biomedical Engineering, Chemical Engineering, Chemistry & Biochemistry, Mechanical Engineering, Microbiology, Pharmaceutics & Pharmaceutical Chemistry and Physics) and four Colleges (Arts and Sciences, Engineering, Medicine and Pharmacy). The C-Trap will significantly advance these NIH funded researchers by enabling them to carry out high impact single molecule studies on a range of molecular and cellular mechanistic questions in fields including HIV infection, chromatin epigenetics, cellular endocytosis, RNA processing, DNA recombination, RNA transcription and the molecular basis of hearing. The major users and technical advisors have extensive relevant expertise with the technology to provide guidance to new users. In addition, Ohio State is committing significant institutional resources (dedicated space and funds for operations and maintenance) to ensure its efficient use. The establishment of resource will significantly enhance numerous research programs at The Ohio State University and eventually throughout Ohio and the Midwest region.